Polypropylene sleeves

During the summer, a theatre here in Valencia donated a series of
boards with a huge collection of signed photographs of actors,
dating back to the beginning of the 20th century. These had been
stapled or nailed to the boards. Once removed, they were placed by
museum curators in polypropylene sleeves and then filed in large
ring binders.

Recently, a curator was amazed to discover that the polypropylene
sleeves had suffered a kind of rippling effect in areas directly in
contact with the photographs.

My impression is that this has been caused by moisture present in
the substrate of the photographs and fluctuations in RH and
temperature, especially since there are no environmental controls in
the area where these photographs are stored. Has anyone had this
kind of reaction? Might there be other factors at play such as pH or
off-gassing from the photographs? Any ideas?

Dylan Cox
Museo de Prehistoria y de las Culturas de Valencia, Spain


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                  Conservation DistList Instance 18:27
                Distributed: Thursday, December 16, 2004
                       Message Id: cdl-18-27-030
                                  ***